comment about #676 fix

I reviewed the fix for #676 and have a comment about it. Unfortunately #676 cannot be reopened, so that is why the new ticket was open.

Why are `timestamp` and `sequence_number` still converted via `float64` ?
https://github.com/influxdb/influxdb/commit/dcc1c9a2e02c9a2a34a243b1a3439813f52bf24e#diff-5f4e7a2764de0f93aa09e2d68927b6aaR71
https://github.com/influxdb/influxdb/commit/dcc1c9a2e02c9a2a34a243b1a3439813f52bf24e#diff-5f4e7a2764de0f93aa09e2d68927b6aaR94
It seems at least superfluous and can cause the same bug (for example with user-generated `sequence_number`)
@jvshahid  Is field time allowed to be a float?  If not, we should just call strconv.ParseInt directly.